Let us discuss today the operation of full wave rectifier:
In the full wave rectifier, two PN junction Diodes (say D1 and D2) a connected in the circuit. A load resistance (RL) is connected in the circuit across which the output is taken.
Let at any instant S1 is positive and S2 is negative. the diode (D1) is forward biased and diode (D2) is reversed biased so D1 will conduct but D2 will not.
In the next half cycle, D1 will be reversed biased whereas D2 will be forward biased so the out put will be due to D2 only. This process goes on and it must be noted the current through the load resistance flows in the same direction and ultimately a constant output is obtained which is a uni-directional pulsating d.c.
This is how a full wave rectifier operates.
Also read: Operation of half wave rectifier.